Abrasive throwing machine



Oct. 19, 1937. v. E. MINICH I ABRASIVE THROWING MACHINE Original FiledMay 26, 1954 3 Sheets-Sheet 1 15/ [13 14 INVENTOR 34 lgrnzi Mimi!ATTORNEYS Oct. 19, 1937. v. E. MINICH Re. 20,538

ABRASIVE THROWING MACHINE 1 Original Filed May 26, 1934 3 Sheets-Sheet 2INVENTOR I Verne [Mt/11th mit/v. Is 75 ATTORNEYS Oct. 19, 1937. v, v Re.20,538

ABRASIVE THROWING MACHINE Original Filed May 26, 1934 3 Sheets-Sheet 3fi 0 4 I. I

L III I INVENTOR ATTORNEYS Reiuued Oct. 19,1937

UNITED STATES ABRASIVE 'rnnownvc mom Verne E. Minich, Scarsdale, N.

Y., assignor to The American Foundry Equipment Company, Mishawaka, Ind.,a corporation of Delaware Original No.

2,077,637, dated April 20, 1937,

rial No. 727,665, May 26, 1934. Renewed January 25, 1937.

Application for reissue August 17, 1937, Serial No. 159,586

14 Claims.

This invention relates to abrasive throwing machines and moreparticularly to a method and apparatus for throwing abrasive at ablasting velocity so as to eflectively clean metal sheets, castings,forgings and the like.

According to this invention the machine is so arranged and constructedas to throw the abrasive fed into the machine at a blasting velocityunder directional control. The machine generally comprises a wheel orrotor having a plurality of throwing blades extending from the peripheryof the wheel inwardly short of the axis of rotation of the wheel. Theblades may be rotatably v supported from either one or a pair of spacedside wall members or discs fixed to a rotatable shaft. The blades areremovable and replaceable through the wheel periphery, suitable meansbeing provided to releasably retain the blades in fixed operativeposition. The abrasive is fed into the path 01' the rotating bladesthrough one or more discharge openings provided in a control memberwhich is adjustably mounted to direct the abrasive thrown from themachine in the desired direction. The control member preferablycomprises a tube positioned centrally of the rotor and mountedindependently thereof. An impeller positioned within the control memberand preferably attached to the rotor for-rotation therewith throws theabrasive through the discharge opening in the control member and intothe path of the rotating vanes 01 the rotor. The impeller generallycomprises a plurality of radially arranged vanes or blades carried bythe rotatable disc of the rotor. The abrasive is fed through a suitablefeed pipe into the impeller and the vanes of the impeller pick up theabrasive and carry the abrasive to the discharge opening in the controlmember through which it thrown into the path of the rotating blades.

The abrasive can be fed into the path of the rotating blades at anydesired point by adjusting the position of the discharge opening in thecontrol member. Directional control is thus accomplished. The dischargeopening is preferably of such form that the abrasive is dischargeduniformly through the entire area of the discharge opening. The lengthof the path of thrown abrasive is determined and controlled by thecircumferential length of the discharge opening. Triangular, ofisetrectangular and obliquely extending slot shaped discharge openings haveproven to be practical and efficient but other shaped slots may be usedto obtain the desired result. Two or more separated surfaces can also becleaned simultaneously by providing two or more properly arrangedopenings in the control member. The control member is preferablyconstructed and mounted so that it can be easily removed and replaced ifdesired by a control member having an opening or openings 01 differentsize or shape. The same machine can thus be used for a variety ofdifferent operating conditions.

An object of this invention is to'provide an abrasive throwing machineprovided with adjustable means by which abrasive may be directionallycontrolled so as to do useful work.

Another object of this invention is to provide an abrasive throwingwheel having adjustable and replaceable parts by means of which thedirection of flight and the area or areas covering the thrown abrasivemay be regulated and controlled and whereby substantial uniformimpingement of the abrasive against the article treated may be attained.

Another object of this invention is to provide a method for throwingabrasive at a blasting velocity and for controlling the direction offlight of and the area covered by the thrown abrasive.

Another object of this invention is to provide an abrasive throwingmachine having associated parts which may be removed and replaced whenworn or injured.

Another object of this invention is to provide an abrasive throwingmachine which is simple in construction, inexpensive to manufacture andproduce, which has a low power consumption for the work done, whichimparts to the abrasive particles a highly effective abrading velocity,which causes a minimum disintegration of the abrasive particles, whichis durable and lasting in construction, which is not subjected toexcessive wear from the abrasive when thrown from the machine, which isprovided with means for -controlling the directional flight and the areacovered by the thrown abrasive, and which is high adaptable for thecleaning of metal sheets, billets, shapes, forgings, castings, metalparts and other articles.

Other objects of this invention will become apparent as the disclosureproceeds.

In order thata clearer understanding of my invention may be had,attention is hereby directed to the accompanying drawings forming a partof this application and illustrating certain possible embodiments of myinvention:

Referring to the drawings:

Fig. 1 is a longitudinal cross sectional view taken through the abrasivemachine showing the interior construction thereof, this view being takenon line I-l of Fig. 2;

Fig. 2 is a transverse cross sectional view through the abrasivemachine, this view being taken on line 2 2 of Fig. 1;

Fig. 3 is a transverse cross sectional view through the abrasive machineshowing more particularly the construction of the control member andimpeller, this view being taken on line 3-3 of Fig. 1;

Fig. 4 is a fragmentary end view of the machine illustratingparticularly one means which may be used to manipulate andhold thecontrol member in any desired operating position;

Fig. 5 is a diagrammatic view illustrating the direction of movement ofthe abrasive thrown from the machine when the discharge opening in theadjustable control member is positioned as shown;

Fig. 6 is a transverse cross sectional view through the abrasive machineequipped with a control member provided with two discharge openingsoperative to throw abrasive on separated surfaces;

Fig. 7 is a fragmentary longitudinal cross sectional view through theabrasive machine shown in Fig. '7, this view being taken on line L4! ofFig. 6;

Fig. 8 is a diagrammatic viewillustrating the direction of movement ofthe abrasive throw from the machine shown in Figures '7 and 8 when thedischarge openings in the control member ,ings and specification.

One of the big difliculties heretofore encountered in the operation ofabrasive throwing wheels results from lack of control over the abrasivethrown therefrom. When the wheel or rotor is operated at a speed of 1800revolutions per minute and upward, the rotor has a tendency to carry aportion of the abrasive arcundwith it and throw the abrasive off intospace where it fails to impinge the work if the abrasive is not brought"under proper directional control before it is thrown. A heavy loss inefficiency thus results, and even more important, particles thrown atrandom soon destroy and abrade away operating parts of the machine orany protective guard placed around the machine. This inventioncontemplates provision of means for placing the thrown abrasive undercontrol so that all abra sive particles may be directed and controlledso as to directly impinge the work with substantially uniformimpingement intensity.

According to this invention abrasive particles, such as sand, steel,filings or shot are fed into an impeller A positioned within a controlmember C centrally mounted within a wheel or rotor. The rotor is mountedupon a rotatable shaft 5 having a hub 6 connected by means of the bolts1 to a side wall member or disc l. Abrasive throwing blades B areprovided which are radially arranged in spaced relationship and extendfrom the periphery of the wheel inwardly short of the axis of rotationof the wheel so as to provide a central opening. The blades may besuitably supported from the side wall member or disc i or if desired theblades may .be suspended between a pair of spaced side wall members Iand I5. When a pair of sidewall discs I and ii are provided they may beheld in fixed spaced relationship by means of suitable connecting vanes2 which may also provide a support for the blades B. Aguard vane 3following the connecting" vane may be provided, bothavanes being joinedtogether by an apex por- Directional control of the abrasive isaccomplished through the provision of the control member C which ispositioned centrally of the rotor and is independently and 'adjustablymounted with respect thereto. The control member 0 comprises generally atubular wall 30 provided with an inturned flange 3| at the inner enuthereof. The outer end of the tubular sidewall 30 extends outside of therotor and is provided with an outturned flange 32. A supporting collar33 surrounds the outer end of the tubular side wall 30 and is so shapedand arranged as to permit rotation of the control member with respectthereto. The supporting collar 33 may be angle shaped in cross section,as shown, or any other suitable shape. The collar member 33 is connectedby means of bolts 39 to a supporting plate 40 extending from theframework which supports the machine. A pair of handles 38, suitablyconnected to the tubular side wall 30 of the control member, may beprovided for adjusting the control member with respect to the rotor.

Suitable means are provided for locking the control member in anydesired adjusted position. As shown more particularly in Figs. 3 and 4,a plurality of key bolts 34 are provided which are hinged to lugs 35extending from the supporting collar 33. Threaded wing nuts 36 whichscrew over threaded end portions 31 of the key bolts 34 seat over theout-turned flange 32 of the control member. By manipulating the wingnuts 36 the control member may be locked in any desired position. Thecontrol member 0 may be adjusted in position by simply loosening thewing nuts 36 and rotating the control member into the desired adjustedposition. The control member is provided with a discharge opening 0through which the abrasive fed into the machine is discharged into thepath of the throwing blades B. The shape and arrangement of thedischarge opening 0 will be discussed more fully hereinafter inconnection with the operation of the machine.

Means are provided for propelling the abrasive fed into the controlchamber into the path 01' the throwing blades through the dischargeopening 0. An impeller A positioned within the control member C rotateswith the rotor. As shown more particularly in Figs. 1 and 3, theimpeller comprises spaced plates 2ll and 2| connected by the radiallyarranged throwing vanes and blades 22. The impeller is operativelyconnected to the rotor of the machine by means of a screw bolt 2| whichextends through the plate 2| and screws into a plate 23 fixed to thedisc i of the rotor by means of screws 25. It is understood, however,that the impeller can be connected to the rotor by other convenientmeans or it may be driven independently. The impeller should be soconnected, however, as to permit removal of the control member whendesired. Removal of the control member may be effected in the assemblyherein shown by removing the screw bolt 24 which permits removal of theimpeller A along with the control member C.

The abrasive is fed into a hopper or funnel I6 from which it passes intoa suitable feed pipe I]. Plate of the impeller is provided with a largeopening 26 through which the feed pipe I I extends. The discharge end I8oi the feed pipe I1 may be contracted into the general shape shown inFigs. 1, 3 and 4 and the discharge opening I9 therein is elongated so asto distribute the abrasive emitted therefrom substantially uniformlyacross the entire width of the throwing vanes 22. It will also be notedthat the inner end of the feed pipe I! is of generally elbow formationso as to direct the abrasive radially across the impeller vanes 22 andout of wearing contact with the impeller plates 20 and 2 I.

In operating the machine a supply of abrasive is fed into the hopper orfunnel it from which it is fed in controlled amounts through the feedpipe II. The abrasive is emitted from the discharge opening I9 of thefeed pipe and is immediately picked. up and carried by the throwingvanes 22 of the impeller until the discharge opening 0 is reached. Theabrasive then escapes through the opening 0.

The shape as well as the position of the discharge opening 0 in thecontrol member C determines to a large extent the length of the pathswept by the abrasive discharged from the machine as well as theuniformity of the discharge. A triangular shaped opening 0, shown moreparticularly in Fig. 2, has been found to effectively control thedirection and uniformity of the abrasive discharge. The apex of thetriangular opening is positioned approximately centrally over theimpeller A and the base of the triangular opening faces the direction ofrotation of the impeller. By referring particularly to Fig. 2, it isseen that the abrasive. carried along by the rotating throwing vanes 22,is distributed uniformly over the width thereof, and is graduallydischarged from the vane and thrown through the triangular shapedopening 0. In other words, the rotating vane first arrives at the apexof the triangular opening with the result that the abrasive deposited onthe center portion of the vane is first thrown through the apex portionof the opening following which the abrasive on both sides of the centerline of the vane is thrown through the expanding triangular shapedopening until all the abrasive carried by the vane has been discharged.The abrasive carried by the vane is discharged through the triangularshaped opening as the vane moves across the opening from the apex to thebase thereof. The distance between the apex and the base of thetriangular shaped opening determines the length of the path swept by theabrasive discharged from the machine. It is also seen that the abrasivepasses through the triangular shaped opening in substantially uniformamounts from the initial discharge through the apex of the triangle tothe base thereof. The isosceles shape of the triangular opening thusdetermines the uniformity as well as the density of the abrasivedischarged therethrough.

The abrasive discharged through the opening 0 is impelled into the pathof the moving throwing blades B. Each blade B, as shown in Figs. 1, 2and 3, is made of heavypwear resisting material and may be mounted uponthe connecting vane 2 within the abrasive discharge passage D. The bladeB lies between the discs I and I5 and extends from the periphery of thecontrol member C to the outer periphery of the rotor. The

blade 13 is in the form of a chute comprising a bottom portion II) whichcovers the connecting vane 2, and side wall portions II which protectthe discs I and I5 from contact with the flying abrasive. Any convenientmeans for removably securing the blades in position may be provided. Forpurposes of illustration, one form of blade securing means is shownwhich comprises a shoulder I2 projecting from the disc I and which seatswithin a groove I3 cut in the side wall II of the blade B. A set screwII extends through the disc member I 5 and engages the side portion I Ito lock the blade in position. Other well known means for removablysecuring the blade in position, however, may be provided within thescope of this invention. The inner end of the blade is positionedadjacent to the tubular side wall of the control member. The inner endportion ll of the side wall portions II are beveled and the underside ofthe bottom portion II) is also beveled, as shown in Fig. 1, to reducethe end of the blade to substantially a fine edge which cleaves theabrasive ejected from the discharge opening and directs the same acrossthe blades and prevents rebound and scattering of the abrasive. Theblade is preferably flared toward the inner end thereof so as to morereadily catch the abrasive emitted from the discharge opening 0.

Two separated surfaces may be cleaned simultaneously by providing two ormore discharge openings in the control member. As shown moreparticularly in Figs. 7, 8 and 9, the control chamber C1 is providedwith a discharge opening 01 and a discharge opening Ox positionedapproximately 180 from the opening first mentioned. With thisarrangement the abrasive emitted from the discharge opening Oi is thrownby the throwing blades B to impinge the work surface W positionedbeneath the machine, and the abrasive emitted from the discharge openingOx is thrown by the blades B so as to impinge the work Wx positionedabove the machine. Two separated surfaces can thus be cleanedsimultaneously by means of a single wheel. It will be understood thatany number of work surfaces arranged at any angle to one another can becleaned by means of a single wheel by providing a control member havingan opening for each work surface, each opening being so arranged as todischarge the abrasive at a point where it will eventually impinge thedesired surface. more discharge openings in the control member may beadvantageously used in the cleaning of tubes, boilers, metal sheets,forgings, castings, billets and other metallic objects having two ormore surfaces to be cleaned. The discharge opening 01 shown in Fig. 6 isrectangular in form. A control member having rectangular openings ofthis type is especially adapted to throw relatively large concentratedquantities of abrasive over a relatively small area.

A control member C2 is shown in Fig. 9 having discharge openings 02 and02x in the shape of right angled triangles, the base of which is axiallyarranged. The circumferential length of the right angled triangulardischarge opening determines the length of the path swept by theabrasive. The rotating throwing blades 22 of the impeller firstdischarge'the abrasive at the apex of the triangle, and, as the bladesprogress across the discharge opening, the abrasive is emitted in a.uniform quantity through the discharge opening until the base of thetriangular discharge opening is reached. The control member Ca may beprovided with one, two or more discharge Wheels having two or openingsdepending upon the number of surfaces to be reached by the abrasive.

There is shown in Fig. 10 a control chamber C4 having a discharge outletcomprising spaced openings 0a and 03y arranged in series. These openingsmay be either rectangular or triangular in shape. If two dischargeopenings are used the width of each discharge opening 03 and 03y isapproximately half the axial width of the impeller A. Considering theimpeller as rotating clockwise, the abrasive is first discharged throughthe opening 03. The openings 03 and 03y are preferably arranged so thatthere is no break in the uniformity of discharge. A path of considerablelength can be cleaned by the provision of two or more rectangulardischarge openings, each covering only a part of the actual width of theimpeller, the openings being offset with respect to one another. Thereshould be a break between the two openings approximately equal to thelength of each opening since the abrasive flowing out of the firstopening spreads fanwise and sufficient interval must be allowed betweenthe openings so that the fans will not overlap if the great est surfacecoverage by the abrasive is to be realized. The offset arrangement ofthe openings as shown in Fig. 10 has produced very advantageous resultswith respect to uniformity of discharge and a long path across the workis swept by the abrasive.

There is shown in. Fig. 11 a control member C4 having a biased slotshaped opening 04. The opening 04 is cut at an angle across the tubularside wall 30 of the control member and extends the full width of theimpeller throwing vanes 22. When a discharge opening 04, as shown inFig, 11, is used, it is seen that the abrasive is dischargedsubstantially uniformly through the openings as the impeller throwingvanes 22 move across the same.

In all cases the axial width of each discharge opening of pluraldischarge openings should be of suflicient width to extend completelyover the side walls of 20 and 2| of the impeller. By making thedischarge opening equal to or larger than the width of the impeller Athe circumferential side margins of the opening are spared the wearwhich otherwise results when the abrasive thrown by the impeller isthwarted in its exit by the overhanging portions along thecircumferential sides of the opening. The axial width of the openingshould, however, be not more, and preferably less, than the width of theblades B so that all the abrasive is guided directly into the path ofthe blades B and out of contact with the permanent parts I and i5 of themachine.

It is understood that a variety of different shaped discharge openingsmay be used within the contemplation of this invention depending uponthe effects to be produced. As a general principle, the opening orarrangement of openings should extend on a bias with respect to theimpeller throwing vanes 22. The circumferential length of the openinggenerally determines the length of the path swept by the abrasive andthe axial shape and width of the slot determines the concentrationintensity and impingement uniformity of the abrasive thrown from thewheel.

The abrasive ejected from the discharge opening 0, O1, Oz, 02, 04 ormodifications thereof is carried by the rotor and thrown or projected bythe throwing blades B. As diagrammatically illustrated in Fig. 5, theabrasive which is first ejected from the dischargre opening is carriedby the throwing blades B a distance of approxithrown abrasive as well asto limit or expand mately to before leaving the outer ends of the bladesto impinge the work W. The abrasive which is last to leave the dischargeopening 0 likewise leaves the ends of the blades B at a pointapproximately 120 to 180 removed from the extreme edge of the dischargeopening. The range of discharge, of course, depends to a considerabledegree upon the length of the discharge passage through which theabrasive has to move after being emitted from the discharge opening inthe control member. The direction of discharge may also vary with thelength of the discharge passage D, as well as the diameter of thecontrol member and general tip blade diameter of the wheel. A wheelhaving a diameter of approximately 19 inches and a control member ofapproximately 5 inches will throw the abrasive approximately as showninFig. 5 when rotated at an abrading speed of 2250 R.-P. M. With atriangular shaped discharge opening having a peripheral length ofapproximately 2 inches, an effective cleaning path of from 2 to 3 feetwill be swept by the abrasive. Different operating effects may beobtained by changing either the shape or size of the discharge openingin the control member. Change in shape and size of the discharge openingcan be effected by either providing adjustable shutters for the openingor by the provision of a removable and replaceable control member havingthe desired type of discharge opening.

With a machine as above constructed substantially all of the abrasivecan be thrown in the direction desired so as to directly impinge thedesired work area and perform effective work. The removable andreplaceable throwing blades are so constructed that none of the abrasiveemitted from the discharge opening is permitted to contact the discs Iand IE or other permanent parts of the machine. The blades B are made ofwear resisting material and will withstand great abuse. When furrowed orotherwise worn by the moving abrasive they may be easily and quicklyremoved and replaced with new shoes.

The machine is adapted for a variety of different uses, such as thecleaning of metal sheets, billets, castings, forgings and otherarticles. The machine may be mounted upon any suitable standard or maybe associated with other apparatus, such as a tumbling mill. The machineis made of few parts, and may be inexpensively manufactured andassembled. Adjustable means are provided which may be easily and quicklymanipulated to directionally control the the path swept by the abrasiveand the intensity of the impingement against the work. The machine isfurthermore strong and durable in construction, substantially foolproofin operation, requires little floor space and is highly efficient.

While certain novel features of the invention have been disclosed andare pointed out in the annexed claims, it will be understood thatvarious omissions, substitutions and changes may be made by thoseskilled in the art without departing from the spirit of the invention.

What is claimed is:

1. A machine for throwing abrasive including in combination, a tubularcontrol member having a discharge outlet in the tubular side wallthereof, and throwing blades radially arranged around said memberoperative to throw the abrasive emitted from said outlet, said dischargeoutlet having one or more edge portions extending progressively axiallyand circumferentially across said tubular side wall.

2. A machine for throwing abrasive including in combination, a tubularcontrol member having a discharge outlet in the tubular side wallthereof, impelling means interiorly of said controlmember forprogressively ejecting abrasive through said discharge outlet andthrowing blades radially arranged around said member operative to throwthe abrasive emitted from said outlet, said outlet extending diagonallyacross the side wall of said member thereby efiecting substantiallyuniform concentration of the abrasive throughout the predetermined pathswept by the abrasive thrown from the machine.

3. A wheel for throwing abrasive including in combination, an adjustablymounted tubular control member having an outlet in the tubular side wallthereof, impelling means interiorly of said control member forprogressively ejecting abrasive through said discharge outlet androtatably mounted throwing blades radially arranged around said memberoperative to throw the abrasive emitted from said outlet, said outletbeing diagonally arranged with respect to said impelling means therebyeffecting substantially uniform concentration of the abrasive throughoutthe predetermined path swept by the abrasive thrown from the wheel.

4. A machine for throwing abrasive including in combination, a tubularcontrol member having a triangular shaped discharge opening extendingcircumferentially across the tubular side wall thereof, and throwingblades radially arranged around said member operative to hurl theabrasive emitted from said opening at blasting velocities.

5. A machine for throwing abrasive including in combination, a tubularcontrol member having an elongated discharge opening extending obliquelyacross a circumferential portion of said member, and throwing bladesradially arranged around said member operative to throw abrasive emittedfrom said opening.

6. A machine for throwing abrasive at blasting velocities including, atubular control member having a discharge opening extending diagonallyacross the tubular side wall thereof, and throwing blades radiallyarranged around said member operative to throw the abrasive emitted fromsaid opening, said discharge opening having an axial width less than thewidth of said throwing blades.

7. A machine for throwing abrasive including in combination, a tubularcontrol member having a triangular shaped discharge opening extendingcircumferentially across the tubular side wall thereof, and throwingblades radially arranged around said member operative to hurl theabrasive emitted from said opening at blast ing velocities, saiddischarge opening having an axial width less than the width of saidthrowing blades.

8. A machine for throwing abrasive at blasting velocities including, atubular control member having one or more discharge openings in thetubular side wall thereof, impelling means interiorly of said controlmember for progressively ejecting abrasive through said discharge outletand throwing blades radially arranged around said member operative tothrow the abrasive emitted from said openings, said openings each havinga side edge thereof extending diagonally across the side wall of saidmember to effect substantially uniform distribution of the abrasive overthe work surface.

9. A machine for. throwing abrasive at blasting velocities including, atubular control member having a discharge opening in the form of anisosceles triangle extending circumferentiallly across the tubular sidewall thereof, and throwing blades radially arranged around said member0perative to hurl the abrasive emitted from said opening at blastingvelocities.

10. A machine for throwing abrasive at blasting velocities including, atubular control member having a discharge opening in the form of a rightangled triangle with the hypotenuse thereof extending circumferentiallyacross the tubular side wall of said member and throwing blades radiallyarranged around said member operative to hurl the abrasive emitted fromsaid opening at blasting velocities.

11. A wheel for throwing abrasive at blasting velocities including, anadjustably mounted abrasive control member having a discharge outlet inthe tubular side wall thereof, rotatably mounted blades radiallyarranged around said member, and an impeller comprising radiallyarranged blades rotatably mounted within said member operative to throwthe abrasive through the outlet and into the path of said rotatingblades, said discharge outlet and impeller blades being diagonallyarranged with respect to one another so that the abrasive is sweptacross different edge portions of the outlet as the impeller bladesprogressively move across the same so as to thereby eifect substantiallyuniform distribution of the abrasive over the work surface.

12. A wheel for throwing abrasive at blasting velocities comprising,throwing blades extending from the periphery of a wheel substantlally tothe circumference of a normally stationary, centrally disposed, tubularcontrol member having an abrasive discharge outlet in the tubular wallthereof, and movable abrasive ejecting means positioned interiorly ofsaid tubular control member, the discharge outlet in said tubularcontrol member being so shaped and arranged as to effect the gradualdischarge of abrasive at a substantially uniform rate to the inner endof each throwing blade as the same travels a single time through apredetermined limited arc of the circumference of said stationarycontrol member, whereby each throwing blade is caused to graduallyreceive at its inner end each charge of abrasive and to discharge fromthe periphery of the wheel a substantially uniform stream ofsubstantially uniform volume over a predetermined area.

13. In an abrading machine, a rotor having a plurality of bladesterminating short of the axis of said rotor to define an abrasiveadmitting space, an abrasive feeding device of an external diameter lessthan the radius of the rotor extending into said space and having adischarge opening therein disposed to one side of the axis of said rotorand located between the planes of rotation defined by the sides of saidblades for delivering abrasive to the inner ends of said blades, saidblades terminating sufficiently close to said feeding device to pick upthe abrasive with a minimum impact and being operable to discharge itfrom the outer ends of said blades at an abrading velocity when saidrotor is rotated, a rotatable impeller comprising a plurality ofimpeller vanes disposed within said feeding device, said dischargeopening and impeller vanes being diagonally arranged with respect to oneanother so that the abrasive is swept across ditierent edge portions ofthe discharge opening as the impeller vanes progressively move acrossthe same, said vanes being joined adjacent said rotor by a generallycircular flange structure, said vanes extending to a region closelyadjacent thevanes, whereby said abrasive retaining flange overhangs theside edges of said impeller vanes to provide a closed chamber withinsaid abrasive feeding device for minimizing abrasive leakage therefrom.

14. A wheelior throwing abrasive at blast ing velocities including, an'adiustably mounted abrasive control member having a discharge outlet inthe tubular side wall thereof, rotatably mounted blades radiallyarranged around said member, and an impeller comprising radiallyarranged blades rotatably mounted within said member operative to throwthe abrasive through the outlet and into the path of said rotatingblades, said discharge outlet and impeller blades being diagonallyarranged with respect to one another so that the abrasive is sweptacross difierent edge portions of the outlet as the impeller bladesprogressively move across the same so as to thereby effect substantiallyuniform distribu tion 01' the abrasive over the work surface, saidcontrol member having an inwardly extending abrasive retaining flangedisposed at the inner ends of said impeller blades and having aninternal diameter. less than the overall external diameter of saidimpeller vanes.

VERNE E. MINICH.

